Reception data synchronizing apparatus and method, and recording medium with recorded reception data synchronizing program

ABSTRACT

A synchronism pattern detecting timing recorder ( 20 ) records a synchronism pattern detecting timing at which a synchronism pattern is detected in reception data, a synchronism decider ( 12 ) collates the reception data with reference data to decide whether or not the reception data is consistent in phase with the reference data, and a timing generator ( 22 ) operates, when the synchronism decider ( 12 ) gives a decision for inconsistency in phase, for a match between the synchronism pattern detecting timing recorded in the synchronism pattern detecting timing recorder ( 20 ), as a subsequent one, and a timing of a synchronism pattern of the expectation data, and the subsequent synchronism pattern detecting timing in record is used to render the phases consistent, allowing for a rapid synchronization to be obtained, without the need of waiting a detection of synchronism pattern, even with an inconsistency in phase due to a false synchronism pattern.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a measurement of bit errors, andparticularly, to acquisition of a synchronization between reception datapast a DUT (Device Under Test) and expectation data by detectingsynchronism patterns contained in the reception data and the expectationdata.

2. Description of the Related Art

In cases of data communications by optical fibers there occurs a casecausing a bit error. It is then necessary to detect the bit error to becorrected. FIG. 8 shows a system arrangement for making a detection ofbit error.

A first pattern generator 52 gives electric data to a DUT (device undertest as an element to be measured) 60. The DUT 60 has an E/O(electric/optic) converter 61, O/E (optic/electric) converter 62, and anoptical fiber 63. The electric data given to the DUT 60 is converted bythe E/O converter 61 into light, which is transmitted through theoptical fiber 63 and returned by the O/E converter 62 again intoelectric data. The data output from the DUT 60 is called reception data.

A second pattern generator 54 generates expectation data for collationwith the reception data. At a collator 56, the reception data iscollated with the expectation data to find part of the reception datainconsistent with the expectation data, if any, as an inconsistent partto be a bit error.

At the collator 56, for collation between the reception data and theexpectation data, there is needed a synchronism to be obtained betweenthe reception data and the expectation data. There is thus detected asynchronism pattern contained in the reception data, and the expectationdata is generated in accordance with the detected timing, therebyobtaining a synchronism.

SUMMARY OF THE INVENTION

However, the reception data contains also a false synchronism pattern,which is not a synchronism pattern, but has like data to the synchronismpattern. Or there is a case in which, due to a bit error of thereception data, a pattern different of data from the synchronism patternis recognized as a synchronism pattern. Such a pattern can also bedeemed as a false synchronism pattern. If an erroneous synchronizationis resulted from a false synchronism pattern, there is an inconsistencyin phase.

It therefore is an object of the present invention to provide areception data synchronizing apparatus that allows a synchronization tobe obtained between reception data and expectation data even with aninconsistency in phase due to a false synchronism pattern.

According to the present invention described in claim 1, a receptiondata synchronizing apparatus for a synchronization to be obtainedbetween reception data having a synchronism pattern for a synchronism tobe obtained and expectation data as an expected value of the receptiondata, includes: a synchronism pattern detecting position recording unitfor recording a synchronism timing at which the synchronism pattern ofthe reception data is detected; a collation and synchronism decisionunit for collating the reception data with reference data to decidewhether or not the reception data is consistent in phase with thereference data; and a synchronism control unit operative, when thecollation and synchronism decision unit gives a decision forinconsistency in phase, for a match between a timing at which thesynchronism pattern is detected after the synchronism timing recorded inthe synchronism pattern detecting position recording unit and a timingof a synchronism pattern of the expectation data.

In a reception data synchronizing apparatus arranged as above-noted,even with an inconsistency in phase between reception data and referencedata, it is after a synchronism timing at which a synchronism patternwhen synchronized is detected that a detection of the synchronismpattern restarts to make the reception data and the reference dataconsistent in phase, thus allowing for the reception data to besynchronized with expectation data even with an inconsistency in phasedue to a false synchronism pattern.

According to the present invention described in claim 2, a receptiondata synchronizing method for a synchronization to be obtained betweenreception data having a synchronism pattern for a synchronism to beobtained and expectation data as an expected value of the receptiondata, includes: a synchronism pattern detecting position recording stepfor recording a synchronism timing at which the synchronism pattern ofthe reception data is detected; a collation and synchronism decisionstep for collating the reception data with reference data to decidewhether or not the reception data is consistent in phase with thereference data; and a synchronism control step operative, when thecollation and synchronism decision step gives a decision forinconsistency in phase, for a match between a timing at which thesynchronism pattern is detected after the synchronism timing recorded inthe synchronism pattern detecting position recording step and a timingof a synchronism pattern of the expectation data.

According to the present invention described in claim 3, acomputer-readable medium embodying a program of instructions forexecution by the computer to perform a reception data synchronizingmethod for a synchronization to be obtained between reception datahaving a synchronism pattern for a synchronism to be obtained andexpectation data as an expected value of the reception data, includes: asynchronism pattern detecting position recording step for recording asynchronism timing at which the synchronism pattern of the receptiondata is detected; a collation and synchronism decision step forcollating the reception data with reference data to decide whether ornot the reception data is consistent in phase with the reference data;and a synchronism control step operative, when the collation andsynchronism decision step gives a decision for inconsistency in phase,for a match between a timing at which the synchronism pattern isdetected after the synchronism timing recorded in the synchronismpattern detecting position recording step and a timing of a synchronismpattern of the expectation data.

According to the present invention described in claim 4, a receptiondata synchronizing apparatus for a synchronization to be obtainedbetween reception data having a synchronism pattern for a synchronism tobe obtained and expectation data as an expected value of the receptiondata, includes: a synchronism pattern detecting position recordingdevice that records a synchronism timing at which the synchronismpattern of the reception data is detected; a collation and synchronismdecision device that collates the reception data with reference data todecide whether or not the reception data is consistent in phase with thereference data; and a synchronism control device operative, when thecollation and synchronism decision device gives a decision forinconsistency in phase, for a match between a timing at which thesynchronism pattern is detected after the synchronism timing recorded inthe synchronism pattern detecting position recording device and a timingof a synchronism pattern of the expectation data.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the arrangement of a reception datasynchronizer according to a first embodiment of the invention;

FIG. 2 is a status transition diagram showing actions of the firstembodiment;

FIG. 3 is a diagram showing an example of obtaining a synchronizationbetween reception data and expectation data of the first embodiment;

FIG. 4 is a block diagram showing the arrangement of a reception datasynchronizer according to a second embodiment of the invention;

FIG. 5 is a status transition diagram showing actions of the secondembodiment;

FIG. 6 is a diagram showing an example of obtaining a synchronizationbetween reception data and expectation data of the second embodiment;

FIG. 7 is a block diagram showing the arrangement of a reception datasynchronizer according to a third embodiment of the invention; and

FIG. 8 is a block diagram showing a system arrangement for performing abit error detection in the prior art.

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

There will be described below a first embodiment of the invention withreference to the drawings. First, there is described the arrangement ofa reception data synchronizer according to a first embodiment. FIG. 1 isa block diagram showing the arrangement of the reception datasynchronizer according to the first embodiment.

The reception data synchronizer 1 includes a collator 10, a synchronismdecider 12, a synchronism pattern detector 14, a synchronism controller16, a synchronism pattern detecting position recorder 18, and a seconddata generator 54.

The collator 10 performs a collation between input reception data andexpectation data, detecting a different data between the two data, bitby bit, that is, for a detection of bit error.

The reception data input to the collator 10 is output from a firstpattern generator 52 via a DUT 60. The DUT 60 includes an E/O(electric/optical) converter 61, an O/E (optical/electric) converter 62,and an optical fiber 63. At both ends of the optical fiber 63 areconnected the E/O converter 61 and the O/E converter 62. To the E/Oconverter 61 is connected the first pattern generator 52, and to the O/Econverter 62, the collator 10. The expectation data input to thecollator 10 is input from the second data generator 54.

The synchronism decider 12 decides whether or not the reception data andthe expectation data have consistent phases, that is, if they are insynchronism. The decision for synchronism is made for a synchronism tobe decided if bit errors detected at the collator 10 are under apredetermined amount. If they are out of synchronism, their phases areinconsistent, causing a great amount of different data. Thus, aconsistency in phase can be decided by this method. The synchronismdecider 12, when deciding phases to be inconsistent, transmits theeffect to a synchronism controller 16 and a synchronism patterndetecting position recorder 18 to be described later.

The synchronism pattern detector 14 is adapted, in a state of thelater-described synchronism pattern detecting position recorder 18providing a permission for a detection of synchronism pattern, fordetecting a synchronism pattern from the reception data to notifyinformation of the detection timing to the later-described synchronismcontroller 16 and the synchronism pattern detecting position recorder18.

The synchronism controller 16 is adapted, when notified of a synchronismpattern detection from the synchronism pattern detector 14, to releasethe second data generator 54 from a reset state and, at a timing atwhich a position of the detected synchronism pattern and a position of asynchronism pattern of the expectation data are consistent, to have thesecond data generator 54 generate the expectation data, permitting thesynchronism decider 12 to make a decision of synchronism. It is furtheradapted, upon reception of a phase inconsistency from the synchronismdecider 12, to reset the second data generator 54, initializing thesecond data generator 54 so that the expectation data stops at apredetermined phase until the resetting becomes released.

The synchronism pattern detecting position recorder 18 records a timing(position) where the synchronism pattern of the reception data isdetected. Further, upon reception of a notification of phaseinconsistency from the synchronism decider 12, it permits thesynchronism pattern detector 14 to detect a synchronism pattern from aposition next to the position in the reception data at which thesynchronism pattern is detected.

Next, there are described actions of the first embodiment by using astatus transition diagram of FIG. 2. Ts0, Tc, and Tw0 are necessarytimes for P2, P4, and P6, respectively. From the first pattern generator52 is input reception data, via the DUT 60, to the synchronism patterndetector 14. At the synchronism pattern detector 14, there is detected asynchronism pattern in the reception data (P2).

The synchronism pattern detector 14 having detected the synchronismpattern in the reception data notifies the synchronism controller 16 andthe synchronism pattern detecting position recorder 18 of information ona timing of the detection (P2→P4). Then, the synchronism controller 16gives a permission for a decision of synchronism to the synchronismdecider 12 (P2→P4).

The synchronism detector 12 decides, depending on an amount of biterrors output from the collator 10, whether the reception data and theexpectation data are in synchronism (P4). If they are in synchronism,the decision of synchronism is continued to be made on the basis of abit error amount (P4 P4).

If they are inconsistent in phase (synchronism disorder), thesynchronism controller 16 resets the second data generator 54 tointerrupt transmission of the expectation data (P4→P6). Then, thedetection of synchronism pattern at the synchronism pattern detector 14is stopped up to a position of synchronism pattern recorded in thesynchronism pattern detecting position recorder 18 (P6).

Upon arrival to the position of synchronism pattern recorded in thesynchronism pattern detecting position recorder 18, the synchronismpattern detecting position recorder 18 gives a permission for adetection of synchronism pattern to the synchronism pattern detector 14(P6→P2), and the synchronism pattern detector 14 detects the synchronismpattern in the reception data (P2). Then, if the synchronism pattern isdetected, the control flow goes to the synchronism deciding state (P4).Like this, even in the case of a failed synchronism due to a falsesynchronism pattern, the synchronization can be redone.

FIG. 3 is an example of reception data and the like. Using FIG. 3, anexemplary procedure is described to show how to obtain asynchronization. The reception data has a synchronism pattern 30 and afalse synchronism pattern 32. The expectation data also has asynchronism pattern 70 and a false synchronism pattern 72. Thesynchronism pattern detecting position recorder 18 has an internalreference timing of an identical period to the reception data and theexpectation data. If the false synchronism pattern 32 of the receptiondata is first mistaken as a synchronism pattern at a position of aninternal reference timing 4, the timing is recorded in the synchronismpattern detecting position recorder 18 and occurrence of the expectationdata starts, causing a transition from the synchronism pattern detectingstate to a synchronism deciding state (P2→P4). The synchronism patterndetected from the reception data is the false synchronism pattern 32,which is different from the true synchronism pattern 30, and hence isdecided to be inconsistent in phase at the synchronism decider 12,causing a transition from the synchronism deciding state to asynchronism pattern detection start timing waiting state (P6), where thesecond data generator 54 is initialized. Next, following an interruptionof synchronism pattern detection up to the synchronism pattern detectingtiming (internal reference timing 4) recorded in the synchronism patterndetecting position recorder 18, there occurs a transition from thesynchronism pattern detection start timing waiting state to asynchronism pattern detecting state (P6 P2). Thereafter, the truesynchronism pattern 30 is detected at a position of an internalreference timing 0, causing a transition from the synchronism patterndetecting state to a synchronism deciding state (P2→P4), where adecision for a phase consistency is given at the synchronism decider 12,with an established synchronism.

It is now assumed that Tw0 is a time interval from the time when it isfailed to obtain a synchronism to a start time of a detection ofsynchronism pattern, Ts0 is a time interval from the start time of thedetection of synchronism pattern to a time when a synchronism pattern isdetected, and Tc is a time interval for deciding whether or not asynchronism pattern of reception data and a synchronism pattern ofexpectation data are identical in phase.

Then, an average sync gain time Tsync0 is about 0.5 Np×(Tw0 inaverage+Ts0 in average+Tc in average), where Np is the number ofsynchronism patterns detected within one period.

According to the first embodiment, even with an inconsistency in phasedue to a false synchronism pattern, the synchronism pattern detectingposition recorder 18 allows for the synchronism pattern detector 14 toredo a detection of synchronism pattern from a timing (position) where aprevious synchronism is obtained, so that a synchronism can be obtainedbetween reception data and expectation data even with a phaseinconsistency.

Second Embodiment

There will be described below a second embodiment of the invention withreference to the drawings. The second embodiment is different in that atiming (position) at which a synchronism pattern in reception data isdetected is recorded in a synchronism pattern detecting timing recorder20, and is used for a synchronization to be redone.

First, there is described the arrangement of a reception datasynchronizer according to the second embodiment. Like parts to the firstembodiment are designated by like reference characters, omitting theirdescription. FIG. 4 is a block diagram showing the arrangement of thereception data synchronizer according to the second embodiment. Likeparts to the first embodiment are designated by like reference numerals,omitting their description.

The reception data synchronizer 1 includes a collator 10, a synchronismdecider 12, a synchronism pattern detector 14, the synchronism patterndetecting timing recorder 20, a timing generator 22, and a second datagenerator 54.

The synchronism decider 12, when deciding phases to be inconsistent,transmits the effect to the synchronism pattern detecting timingrecorder 20 to be described later.

The synchronism pattern detector 14 detects a synchronism pattern fromreception data, and makes a notification of the effect to thesynchronism pattern detecting timing recorder 20 to be described later.

The synchronism pattern detecting timing recorder 20 is notified of adetection of the synchronism pattern from the synchronism patterndetector 14. Then, it receives an internal reference timing of thereception data synchronizer 1, from the timing generator 22 to bedescribed later. Then, it records the internal reference timing at thetime when the synchronism pattern is detected. Further, upon receptionof a notification of phase inconsistency from the synchronism decider12, it transmits the internal reference timing at the time when thesynchronism pattern is detected, to the timing generator 22.

Upon reception of the internal reference timing at the time when thesynchronism pattern is detected, the timing generator 22 gives apermission for synchronism decision to the synchronism decider 12.Moreover, it makes the second data generator 54 transmit therefromexpectation data so that a position of a synchronism pattern of theexpectation data coincides with a position of the detected synchronismpattern. Further, it sends a predetermined reference timing signal(called an internal reference timing) to the synchronism patterndetecting timing recorder 20.

Next, there are described actions of the second embodiment by using astatus transition diagram of FIG. 5. Tjdg is a required time at P4,while the Tjdg is substantially equal to Tc.

From the first pattern generator 52 is input reception data, via a DUT60, to the synchronism pattern detector 14. At the synchronism patterndetector 14, there is detected a synchronism pattern in the receptiondata (P2).

The synchronism pattern detector 14 having detected the synchronismpattern in the reception data notifies the synchronism pattern detectingtiming recorder 20 of the effect and a position of the synchronismpattern in the reception data. The synchronism pattern detecting timingrecorder 20, receiving those, outputs to the timing generator 22 asignal (as synchronism pattern timing information) indicating a timingof detection of the synchronism pattern (P2 P4). Then, the timinggenerator 22 responds to the synchronism pattern timing information bycontrolling the second data generator 54 so that the position of thedetected synchronism pattern of the reception data and the position ofthe synchronism pattern of the expectation data coincide with eachother, and by giving a permission for a decision of synchronism to thesynchronism decider 12 (P2→P4).

The synchronism detector 12 decides, depending on an amount of biterrors output from the collator 10, whether the reception data and theexpectation data are in synchronism (P4). If they are in synchronism,the decision of synchronism is continued to be made on the basis of abit error amount (P4→P4).

If they are inconsistent in phase (synchronism disorder), there is takenone of different processes depending on whether a subsequent synchronismpattern has already been detected or not. If an internal referencetiming at the time when the synchronism pattern was detected has alreadybeen recorded in the synchronism pattern detecting timing recorder 20(P4→P5), the timing generator 22 controls the second data generator 54so that the synchronism pattern of the expectation data is matched withthe internal reference timing at the time when the synchronism patternwas detected (P5). Then, when the matching of the synchronism pattern ofthe expectation data is finished (P5→P4), the control flow returns tothe decision on whether or not synchronized (P4).

Unless an internal reference timing at the time when the synchronismpattern was detected has already been recorded in the synchronismpattern detecting timing recorder 20 (P4→P7), there is kept a waiting(P7) until an internal reference timing at the time when the synchronismpattern is detected is recorded in the synchronism pattern detectingtiming recorder 20. Then, the synchronism pattern detecting timingrecorder 20 sends an internal reference timing at the time when thesynchronism pattern is detected to the timing generator 22, and there ismade a decision of synchronism (P7→P2→P4).

Upon arrival to a position of synchronism pattern recorded last time,the synchronism pattern detecting timing recorder 20 restarts recordinga detection timing of synchronism pattern (P6→P2). Then, if asynchronism pattern is detected, the control flow goes to a synchronismdeciding state (P4). Like this, even in the case of a failed synchronismdue to a false synchronism pattern, the synchronization can be redone.

FIG. 6 is an example of reception data and the like. Using FIG. 6, anexemplary procedure is described to show how to obtain asynchronization. The reception data has a synchronism pattern 30 andfalse synchronism patterns 40, 42. The expectation data also has asynchronism pattern 70 and false synchronism patterns 80, 82.

First, if the false synchronism pattern 40 is mistaken as thesynchronism pattern 30 by the synchronism pattern detector 14 (P2→P4),the timing generator 22 controls the second data generator 54 so thatthe synchronism pattern 70 of the expectation data is matched with atiming (position) 4 of the false synchronism pattern 40, to transmit theexpectation data. Then, there is made a decision of synchronism betweenthe reception data and the expectation data (P4), FIG. 6( a).

As a result, with no synchronism obtained, phases are inconsistent.However, as a timing (position) 7 of the false synchronism pattern 42 isrecorded in the synchronism pattern detecting timing recorder 20(P4→P5), FIG. 6( b), the timing generator 22 controls the second datagenerator 54 so that the synchronism pattern 70 of the expectation datais matched with the timing (position) 7 of the false synchronism pattern42, to transmit the expectation data. Then, there is made a decision ofsynchronism between the reception data and the expectation data (P4),FIG. 6( c).

As a result, with no synchronism obtained, phases are inconsistent.However, as a timing (position) 12 of the synchronism pattern 30 isrecorded in the synchronism pattern detecting timing recorder 20(P4→P5), FIG. 6( d), the timing generator 22 controls the second datagenerator 54 so that the synchronism pattern 70 of the expectation datais matched with the timing (position) 12 of the synchronism pattern 30,to transmit the expectation data. Then, there is made a decision ofsynchronism between the reception data and the expectation data (P4),FIG. 6( e).

Now, with a synchronism obtained, there is continuously made a decisionof synchronism (P4→P4).

According to the second embodiment, even with false synchronismpatterns, the second data generator 54 can generate expectation data fora synchronization to be redone, in accordance with a timing when asynchronism pattern recorded in the synchronism pattern detecting timingrecorder 20 is detected, so that a synchronism can be obtained betweenreception data and expectation data.

Further, in the second embodiment, a sync gain time is (an averagerequired time for a single decision of phase consistency)×Np at thelongest, or 0 at the shortest, and an average sync gain time is (theaverage required time for a single decision of phase consistency)×Np/2.The average required time for a single decision of phase consistency issubstantially equal to an average of Tc, and can be shortened by 0.5Np×(Tw0 in average+Ts0 in average) in comparison with the firstembodiment. Thus, the average sync gain time can be rendered small.Therefore, bit errors can be detected in a short bit sequence such as aburst data.

For example, assuming a case of data having a pattern length of 1 Mbits, a data rate of 100 Mbps, and an Np of 10, then Tw0 is 0 at theshortest or identical in time to one period of data at the longest.Therefor, an average Tw0 is (one period of data)/2. An average Ts0 is(one period of data)/(2*Np) (Ts0 to be 0 at the shortest or one periodof data/Np at the longest). Therefore, in the first embodiment, Tw0 inaverage=(1 M/100M)/2=0.005 [s]=5 [ms], Ts0 in average=(1 M/100M)/(2×10)=0.0005 [s]=0.5 [ms], and Tc in average=1 [ms]. Therefore, theaverage sync gain time=(10/2)×(5+0.5+1)=32.5 [ms]. On the other hand, inthe second embodiment, the average sync gain time=(10/2)×Tc=5 [ms]. Aswill be seen from this example, the average sync gain time in the secondembodiment is shorter than the average sync gain time in the firstembodiment.

Third Embodiment

There will be described below a third embodiment of the invention withreference to the drawings. In comparison with the second embodimentusing the synchronism pattern detecting timing recorder 20, the thirdembodiment is different in that it uses a phase difference recorder 26for recording a phase difference between a detected synchronism patternand an initially detected synchronism pattern or a phase differencebetween a detected synchronism pattern and a synchronism patterndetected in a previous time.

First, there is described the arrangement of a reception datasynchronizer according to the third embodiment. Like parts to the firstembodiment are designated by like reference characters, omitting theirdescription. FIG. 7 is a block diagram showing the arrangement of thereception data synchronizer according to the third embodiment. Likeelements to the first embodiment are designated by like referencenumerals, omitting their description.

The reception data synchronizer 1 includes a collator 10, a synchronismdecider 12, a synchronism pattern detector 14, a timing generator 22, aphase difference detector 24, the phase difference recorder 26, and asecond data generator 54.

The phase difference detector 24, having received a notification of adetected synchronism pattern from the synchronism pattern detector 16,detects a phase difference between the detected synchronism pattern andan initially detected synchronism pattern or a phase difference betweenthe detected synchronism pattern and a synchronism pattern detected in aprevious time, and sends it to the phase difference recorder 26 to bedescribed later. The phase difference recorder 26 records the phasedifference detected by the phase difference detector 24.

Actions of the third embodiment are analogous to the second embodiment,but for the difference that a phase difference is used. The phasedifference is used for changing phases of expectation data (P5, see FIG.5). As a description using an example of FIG. 6, in the secondembodiment, the synchronism pattern 70 of the expectation data ismatched with the internal reference timings 4, 7, and 12, one by one inthis order.

In the third embodiment, there are recorded in the phase differencerecorder 26 a timing 4 at which a synchronism pattern is initiallydetected, a difference 3 (7−4) between a timing at which the synchronismpattern is detected twice and the timing at which the synchronismpattern is initially detected, and a difference 8 (12−4) between atiming at which the synchronism pattern is detected thrice and thetiming at which the synchronism pattern is initially detected, andunless a synchronism is obtained at the timing 4, the timing of thesynchronism pattern 70 is shifted by 3 to make a decision of synchronismat a resultant timing, and unless a synchronism is then obtained, thetiming of the synchronism pattern 70 is shifted by 8 from the initial tomake a decision of synchronism at a resultant timing.

Or, in the third embodiment, there are recorded in the phase differencerecorder 26 the timing 4 at which the synchronism pattern is initiallydetected, the difference 3 (7−4) between the timing at which thesynchronism pattern is detected twice and the timing at which thesynchronism pattern is initially detected, and a difference 5 (12−7)between the timing at which the synchronism pattern is detected thriceand the timing at which the synchronism pattern is detected twice, andunless a synchronism is obtained at the timing 4, the timing of thesynchronism pattern 70 is shifted by 3 to make a decision of synchronismat a resultant timing, and unless a synchronism is then obtained, thetiming of the synchronism pattern 70 is further shifted by 5 to make adecision of synchronism at a resultant timing.

Like effects to the second embodiment can be achieved by the thirdembodiment also.

According to the present invention, there can be obtained asynchronization between reception data and expectation data even with aninconsistency in phase due to a false synchronism pattern.

1. A reception data synchronizing apparatus for a synchronization to beobtained between reception data having a plurality of synchronismpatterns and expectation data as an expected value of the receptiondata, comprising: a synchronism pattern detecting position recordingmeans for recording a first synchronism timing at which a first of theplurality of synchronism patterns of the reception data is detected; anda collation and synchronism decision means for collating the receptiondata with the expectation data to decide whether or not the receptiondata is consistent in phase with the expectation data according to thefirst synchronism timing, wherein the synchronism pattern detectingposition recording means, when the collation and synchronism decisionmeans gives a decision for inconsistency in phase, records a secondsynchronism timing, said second synchronism timing being a timing atwhich a second of the plurality of synchronism patterns is detectedafter the first synchronism pattern, which is recorded in thesynchronism pattern detecting position recording means as the firstsynchronism timing, is detected again.
 2. A reception data synchronizingmethod for a synchronization to be obtained between reception datahaving a plurality of synchronism patterns and expectation data as anexpected value of the reception data, comprising: a synchronism patterndetecting position recording step for recording a first synchronismtiming at which a first of the plurality of synchronism patterns of thereception data is detected; and a collation and synchronism decisionstep for collating the reception data with the expectation data todecide whether or not the reception data is consistent in phase with theexpectation data according to the first synchronism timing, wherein thesynchronism pattern detecting position recording step, when thecollation and synchronism decision step gives a decision forinconsistency in phase, records a second synchronism timing, said secondsynchronism timing being a timing at which a second of the plurality ofsynchronism patterns is detected after the first synchronism pattern,which is recorded in the synchronism pattern detecting positionrecording step as the first synchronism timing, is detected again.
 3. Acomputer-readable medium embodying a program of instructions forexecution by a computer to perform a reception data synchronizing methodfor a synchronization to be obtained between reception data having aplurality of synchronism patterns and expectation data as an expectedvalue of the reception data, comprising: a synchronism pattern detectingposition recording step for recording a first synchronism timing atwhich a first of the plurality of synchronism patterns of the receptiondata is detected; and a collation and synchronism decision step forcollating the reception data with the expectation data to decide whetheror not the reception data is consistent in phase with the expectationdata according to the first synchronism timing, wherein the synchronismpattern detecting position recording step, when the collation andsynchronism decision step gives a decision for inconsistency in phase,records a second synchronism timing, said second synchronism timingbeing a timing at which a second of the plurality of synchronismpatterns is detected after the first synchronism pattern, which isrecorded in the synchronism pattern detecting position recording step asthe first synchronism timing, is detected again.
 4. A reception datasynchronizing apparatus for a synchronization to be obtained betweenreception data having a plurality of synchronism patterns andexpectation data as an expected value of the reception data, comprising:a synchronism pattern detecting position recording device that records afirst synchronism timing at which a first of the plurality ofsynchronism patterns of the reception data is detected; and a collationand synchronism decision device that collates the reception data withthe expectation data to decide whether or not the reception data isconsistent in phase with the expectation data according to the firstsynchronism timing, wherein the synchronism pattern detecting positionrecording device, when the collation and synchronism decision devicegives a decision for inconsistency in phase, records a secondsynchronism timing, said second synchronism timing being a timing atwhich a second of the plurality of synchronism patterns is detectedafter the first synchronism pattern, which is recorded in thesynchronism pattern detecting position recording device as the firstsynchronism timing, is detected again.